The Siamese is one of the first distinctly recognized breeds of Oriental cat. The origins of the breed are unknown, but it is believed to be from Thailand. In Thailand, where they are one of several native breeds, they are called Wichian Mat (??????????, a name meaning "moon diamond" ). In the 20th century the Siamese cat became one of the most popular breeds in Europe and North America.
The Thai or traditional Siamese shares some features with the Modern Siamese (e.g., the colour pattern and the short single coat, although not so short and "painted on" as the modern) but differs from it in head and body type. It has a "foreign" type (rather elongated, high on the legs, lithe but substantial, with medium boning) not an "oriental" type as in the modern Siamese and Oriental breeds) and it has a modified wedge head, with rounded cheeks from which project a wedge shaped muzzle (or "marten face" as it was called in 19th century descriptions). The ears are moderately large but not huge, and are placed higher than those of the modern Siamese ears are. The eyes are medium to slightly large, a full almond shape but not extremely "oriental."
Modern Seal Lynx Point Siamese
The breed standard of the Modern Siamese indicates an elegant, slim, stylish, flexible, and well- muscled body. Its head is triangular shaped, with a thin snout. The eyes are almond-shaped and oblique, with large wide based ears positioned more towards the side of the head. This positioning should form a perfect triangle from the tip of the nose to each tip of the ear. It has a long elegant neck, body, and wispy slender tail. The fur is short, glossy, fine, soft, tight, and adhered to the body with no undercoat. The Siamese is characterized by its typical pointed color scheme.
The pointed pattern is a form of partial albinism, resulting from a mutation in tyrosinase, an enzyme involved in melanin production. The mutated enzyme is heat-sensitive; it fails to work at normal body temperatures, but becomes active in cooler areas of the skin. This results in dark colouration in the coolest parts of the cat's body, including the extremities and the face, which is cooled by the passage of air through the sinuses. All Siamese kittens, although pure cream or white at birth, develop visible points in the first few months of life in colder parts of their body. By the time a kitten is four weeks old, the points should be clearly distinguishable enough to recognise which colour they are. Siamese cats tend to darken with age, and generally, adult Siamese living in warm climates have lighter coats than those in cool climates. Originally the vast majority of Siamese had seal(extremely dark brown, almost black) points, but occasionally Siamese were born with blue (a cool grey) points, genetically a dilution of seal point; chocolate (lighter brown) points, a genetic variation of seal point; or lilac (pale warm gray) points, genetically a diluted chocolate. These colours were at first considered "inferior" seal points, and were not qualified for showing or breeding. All of these shades were eventually accepted by the breed associations, and became more common through breeding programmes specifically aimed at producing these colours. Later, outcrosses with other breeds developed Siamese-mix cats with points in other cat colours and patterns including Red and Cream point, lynx (tabby) point, and tortoise-shell ("tortie") point.In the United Kingdom, all pointed Siamese-style cats are considered part of the Siamese breed. In the United States, the major cat registry, the Cat Fanciers' Association, considers only the four original colourations as Siamese: seal point, blue point, chocolate point, and lilac point. Oriental cats with colourpoints in colours or patterns aside from these four are considered Colorpoint Shorthairs in the American cat fancy.
This Siamese cat demonstrates the once common cross-eyed
trait that has largely been bred out.
Many Siamese cats from Thailand had a kink in their tails but over the years, this trait has been considered a flaw and breeders have largely eradicated it, although it persists among street cats in Thailand. Many early Siamese were cross-eyed to compensate for the abnormal uncrossed wiring of the optic chiasm, which is produced by the same albino allele that produces coloured points. Like the kinked tails, the crossed eyes have been seen as a fault and due to selective breeding the trait is far less common today.